Water distillation apparatus with distillate quality sensing control



8.26, 19694 F.TqRANDE-L.. 3,463,706

' VIATEREDISTILLATION APPARATUS WITH DISTILLATE QUALITY SENSING CONTROL FledSept. 18, 1967 x FILTER* Inventor FoRRas-r THompsoN RANunLL A Harney 5 United States Patent O U.S. Cl. 202-202 3 Claims ABSTRACT F THE DISCLGSURE Apparatus for producing fresh water from brine including an evaporator, a distiller, and a distillate quality sensing device, the distillate produced, when of satisfactory quality being removed from a distillate reservoir by a pump and passed to a fresh water tank, and when of unsatisfactory quality being recirculated, with the pump stopped, to the evaporator.

This invention relates to a method of and apparatus for controlling the discharge of distillate particularly fresh water from distillation apparatus comprising an evaporation section including heating means for the liquid to be distilled, a condensing section including vapour cooling means, a distillate reservoir in the condensing section, a reservoir in the evaporation section for liquid to be distilled, and pumping means for withdrawing the distillate from the distillate reservoir. The aforesaid distillation apparatus is hereinafter referred to as distillation apparatus of the type aforesaid.

In a previously proposed arrangement, the distillate discharge pump operated continuously and, if the distillate was unsatisfactory, a dump valve in the pump outlet was actuated to direct the distillate to waste, this being wasteful and uneconomic.

According to the present invention there is provided a method of controlling the discharge of distillate from distillation apparatus of the type aforesaid comprising measuring the quality of distillate from the distillate reservoir and automatically controlling the operation of said pumping means to cause the discharge of distillate to stop if the quality of distillate is below that desired, and to star-t or restart when the quality of distillate is at or above that desired, the unsatisfactory ydistillate being fed back to the evaporation section for re-distillation.

According to another aspect of the invention there is provided apparatus for controlling the discharge of distillate from distillation apparatus of the type aforesaid, comprising control means for controlling the operation of the pumping means, means for diverting the distillate discharge to the evaporation section reservoir, and distillate quality sensing means in communication with said control means, the arrangement being such that if the quality of distillate is below that desired the sensing means signals the control means to cause the discharge of distillate by the pumping means to stop and the distillate discharge to be diverted to the evaporation section reservoir, and if the quality of distillate is at or above that desired the sensing means signals the control means to cause the discharge of distillate by the pumping means to be started or restarted.

Preferably the quality sensing means is in a conduit connecting the distillate reservoir with the pumping means.

Preferably further an overflow conduit is provided adjacent the distillate conduit to receive unsatisfactory distillate overflowing therefrom, the overow conduit being ice adapted to discharge its contents to the reservoir in the evaporation section.

An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawing which is a schematic side view of distillation apparatus according to the present invention.

The illustrated apparatus is for producing fresh water from salt water (brine) and includes a vertically disposed chamber having an evaporation section 1 situated at the base thereof and a condensing section 2 situated above the evaporation section. Filters 3 are provided at the inlet to the condensing section and in the path of upiiowing vapour from the evaporation section.

A casing 4 at the base of the evaporation section provides a reservoir for liquid to be distilled, and the raw feed water inlet conduit 5 connects into the reservoir 4. A distillate overflow conduit 6 is provided connecting with the `conduit 5.

A bank of vertical riser tubes 7 enclosed in a casing 8 connects the reservoir 4 with the vapour space of the evaporation section 1 from which excess brine can be drained through conduit 9 under the influence of a jet pump 10. Heating medium, which is preferably steam or hot water, is passed into the casing 8 through an inlet 11, circulates around the tubes 7 to cause evaporation of the brine therein and passes out again through an outlet 12.

The condensing section includes a reservoir 20 for distillate, conduits 13 and 14 connecting this reservoir 20` with pump 15. During normal operation when the distillate is of the desired quality and pump 15 is in operation the U-section 23 of conduit 6 will act as a gas seal between conduit 13 and reservoir 4. When the distillate is not of the desired purity and pump 15 is out of operation, conduit 6 will allow the unsatisfactory condensate from reservoir 20 to be fed back to reservoir 4 for redistillation in the evaporating section 1. The condensing section has also a bank of U-tubes 16 extending horizontally int-o the condensing section and serving for the throughfiow of cooling waters.

The pump 15 is motor driven and is provided to draw off the distillate from the distillate reservoir 20 and direct same to a fresh water storage tank (not shown) a nonreturn valve 17 being provided in the outlet from the pump to prevent the sucking back of fresh water. The pump motor 18 which could be for example, either an electrical motor or an internal combustion engine, has its operation controlled by an on-off switch. A distillate quality sensing device includes a probe 19 situated within the distillate at the conjunction of conduits 13 and 6 such that it is contiguous with the distillate therein, and a salinometer 21 in communication with the on-off controller 22 for the motor 18.

The distillation apparatus operates as follows: brine is evaporated in the evaporation section 1 and the vapour produced driven off upwards through the filters 3 wherein impurities are removed; the purified vapour is passed into the condensing section 2, and the vapour is condensed, and distillate formed is precipitated into the distillate reservoir 20. The motor controller 22 will have been set to start the motor and pump-in operation but, if the distillate is not of the required quality, then sensing device 19, 21 will signal the controller 22 to cause same to return to the stop position. Consequently, the pump 15 will remain immobile, and the distillate will not be discharged to the fresh water tank.

Distillation will continue and the fresh distillate, if it is not of appropriate quality, will flow to the reservoir 4.

When the distillate in the conduit 1 3 reaches the required quality then the switch will be signalled to cause starting of the pump and discharge of that distillate.

If the distillate produced continues to be of unsatisfactory quality, then there will continue to be a ow of same to the reservoir 4 for re-dstillation. This recirculation of the distillate will continue until the distillate in the conduit 13 reaches the required quality when the pump will be signalled to start and the distillate discharged to the fresh water tank.

I claim:

1. Apparatus for controlling the discharge of distillate, particularly fresh water, from distillation apparatus of the type comprising an evaporation section including heating means for the liquid to be distilled, a condensing section including vapour cooling means, a distillate reservoir in the condensing section, a reservoir in the evaporation section for liquid to be distilled, pumping means connected to said distillate reservoir by discharge conduit to Withdraw distillate from the distillate reservoir, said apparatus including means for controlling the operation of the pumping means; a branch conduit leading olf from the discharge conduit connecting the pump to the distillate reservoir, said branch conduit communicating with the evaporation section reservoir; distillate quality sensing means in the discharge conduit and in communication with said control means; and distillate seal means in said branch conduit to prevent sucking back of fresh feed liquid during the operation of the pumping means; the arrangement being such that if the quality of distillate is below that desired the sensing means signals the control means to canse the discharge of distillate to stop, by stopping the pumping means and the distillate dis- References Cited UNITED STATES PATENTS 2,487,884 1l/l949 Lunt 202-202 X 2,960,449 ll/l960 Williamson 202-163 3,074,216 l/l963 Loebel 55-185 3,235,469 2/1966 Parke 203-2 3,259,552 7/l966 Goeldner 203-3 3,325,376 6/1967 Eckert 202-158 FOREIGN PATENTS 743,451 l/ 1956 Great Britain.

NORMAN YUDKOFF, Primary Examiner F. E. DRUMMOND, Assistant Examiner U.S. Cl. X.R. 202--205; 203-1 

